incorrect sourcepos for list node between code blocks

[akiomik]

Description

When a list is positioned between fenced code blocks, the List node's sourcepos incorrectly ends at the list marker position instead of spanning to the end of the list content.

```
code
```
- list
```
code
```

• expected: List sourcepos should be 4:1-4:6
• actual: List sourcepos is 4:1-4:3

NOTE: The Item node and its children appear to have correct sourcepos (4:1-4:6, 4:3-4:6).

Test Case

#[test]
fn test_list_sourcepos_bug_between_code_blocks() {
    let markdown_input = r#"```
code
```
- list
```
code
```"#;

    let arena = Arena::new();
    let options = Options::default();
    let root = parse_document(&arena, markdown_input, &options);

    let list_node = root.descendants()
        .find(|d| matches!(d.data().value, NodeValue::List(_)))
        .unwrap();

    let actual_sourcepos = list_node.data().sourcepos;

    // This fails: expected 4:1-4:6, got 4:1-4:3
    assert_eq!(actual_sourcepos, sourcepos!((4:1-4:6)));
}

Environment

• comrak: 0.48.0

[akiomik]

I'm not sure if this is related to the original issue, but I discovered another similar sourcepos bug.

Description

Parent list sourcepos ends before child list when nested lists are followed by code blocks.

1. list
    * nested list
```
code
```

• expected: Parent List sourcepos should be 1:1-2:17
• actual: Parent List sourcepos is 1:1-2:7

Note that the Child List's position are correctly 2:5-2:17.
The parent sourcepos should contain the child completely, but it ends prematurely after the nested list marker.

[kivikakk]

Thank you for these reports! I'll look into them soon. Also cc'ing @Martin005 as an FYI, since I know you rely on this too.